Fluid pressure control mechanism



Aug. 21,1945. R. R. STEVENS FLUID PRESSURE CONTROL MECHANISM Filed oct. 2e. 1942 2 Sheets-Sheet 1 www/m.

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' INVENTOR I Rog B Sneuens ATTORNEY Aug. 21, 1945. R. R. STEVENS FLUID PRESSURE CONTROL MEGHANISM Filed Oct'. 29. 1942 2 Sheets-Sheet 2 mmf v INVENTOR EA130 Rceuens AT"TORNEY Patented Aug. 2l, 1945 UNITED "STATES PATENT OFFICE p 2,383,278 FLUID PRESSURE CONTROL MEonANrsM Roy'R. Stevens, Forest Hills, Pa., assignor to The v Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application ctober 29, 1942, ,Serial No. 463,792 5 claims. Y com21-3s) neutral position is aforward startingpo'sition for putting the engine in motion in a direction to cause movement of the craft forwardly, a control zone for varying Hthe amount of fuel supplied to the engine to govern the speed or power output of the engine, and a stop position for cutting oil the supply of fuel to the engine for causing same to stop. At the opposite side of neutral position there is another lstarting position for putting the engine in motion in the Areverse direction to cause astern movement of the craft, a control zone for varying the4 power output or speed of the engine operating in this everse direction, and an engine stopping posi- One Object of the invention is the provision of a fluid pressure power system for selectivelyv controlling the positioning of a multi-position device, such as the maneuvering gear just described.

Another object of the invention is the provision of a fluid pressure system providing for selective positioning of a maneuvering gear or the like from a remote control station such as the deck or pilot house of a marine craft.

Another object of the invention is` the provision of a remote control pneumatic power positioning system for a maneuvering gear or the like so constructed as to provide prompt and accurate positioning of the gear in response to different selected operations of an operator.

According to the above objects I provide a pneumatic remote control system for selectively causing prompt and accuratemovement of a device to be controlled to any selected one of a plurality of positions. This system is associated, for illustrative purposes only, with a maneuvering gear such as above described and embodies a manually operable selector device arranged to be located in the pilot house of a marine craft and connected for remotely controlling a prime mover located at the engine in the craft for controlling the maneuvering gear associated with said engine,

y said prime mover being operative in response to manualpositioning of said selector device to correspondingly position said maneuvering gear.

Different maneuvering gears or other similar devices may have positions which differ in number, function, and disposition from the positions of the specific maneuvering gear above described, but the invention with suitable modification within its scope is equally applicable to the control of such gears or devices as to the structure used l for illustration, as will be readily apparent to those skilled in the are from the description to follow.

Other objects and advantages will be apparent from the following more detailed description of the invention.

In the accompanying drawings, Fig.. l is a diagrammatic view, partly in section and partly in outline, of the improved remote control system arranged for controlling the maneuvering gear of a marine craft; and. Fig. 2 is a cross-sectional view of the power means shown in Fig. 1 emy ployed for actuating the maneuvering gear to its different controlling positions.

K Dc-zscri'l'iton` In the drawings the `reference numeral l indicates a rockable `Acontrol shaft of a maneuvering direction, while rotation in the opposite direction gear, such as used on marine craft, and the numeral 4 indicates a wheel for turning said shaft to different positions to control the starting of an internal combustion engine in either one direction or in the reverse direction, dependent upon the desired direction of movement of the craft, and to then control or vary the power output or speed ofthe engine, and to stop the engine when desired. 'I'hese different positions may be indicated by a pointer 3 associated with wheel 4 and suitable legends applied to a stationary index head 2. as shown in the drawings, it being noted that rotation of the wheel in a clockwise direction from Neutral" position is arranged to provide for movement of the craft in an Ahead isarranged to provide for Astern movement of the craft. At both of the opposite sides of Neutral position there is a Start position for putting the engine in motion in either one direction or the reverse direction, a Full position to obtain maximum engine output, a Slow position to provide for operation of the engine at a chosen reduced output or at an idling speed, and a "Stop position for stopping the engine. `The space between the legends "Fu1l and Slow at each side of Neutral position constitutes a zone for obtaining differentdegrees; of' engine output tre-sacra l 'nie piston n is shown m mg. 2in a. neutral or speed between the maximum. andminimuxn or idling.

The invention comprises remote controlled power meanslfor moving any member such as the wheel `4 and shaft I promptly and with accuracy to any selected one of a plurality of positions such as the positions Just described for shaft I and wheel 4. The means controlled by shaft I.for controlling the engine are therefore not essential to a clear understanding of the invention, and will not be furtherv discussed.

In practice the wheel 4' and shaft I are mounted directly on vthe engine to be controlled. According to the invention I provide the wheel 4 with sprocket teeth and secure directly to the engine and preferably over the wheel 4 a plate or panel for carrying a power means to actuate the sprocket wheel 4 .to turn the shaft I to its diilerent positions. A manual selector ,device 8 is provided for controlling the operation of this power means. The selector device 8 may be located at any suitable station as in the pilot house oi' the craft and thus remote from the power means and engine to be controlled.

I'he power means carried by the panel 5 comprises a sprocket wheel 1 which is journaled on a shaft 8 secured to said panel. This sprocket wheel is preferably identical with the sprocket wheel 4 and is aligned therewith. and the two wheels are connected together by a chain 3`for rotation in unison. A pinion gear III secured to sprocket wheel 1l has driven engagement with a gear sector I I which is journaled on a pin I2 secured to .the panel 5. Rotation of the sector I I in either one direction or the opposite from a neutral position `shown will therefore operate the sprocket wheels 1 and 4 to turn the maneuvering gear' shaft Ito the different positions above described, as will beapparent. A pointer I3 ilxed against turning to the end of shaft 8 overlies the adjacent portion of gear sector II for registering with lines or legends which may be located on said sector, as shown in Fig. 2, to correspond with the different positions of the maneuvering gear shaft I.` The main purpose of pointer I3 is to insure that the' gear sector II will be in its neutral position shown at the time the chain 8 is applied to the sprocket vwheels 4 and 1 with the Wheel 4 in its neutral position shown, so as to insure exact positioning of the maneuvering gear shaft I for different position oi the gear sector II.

For`operating the gear sector II, I mount on the panel 5 a pneumatic control motor I5 -which comprises a power cylinder I6 containing a double acting piston I1 having at one side a pressure chamber I8 connected to a passage I8 lchamber 20 connected to a passage 2|.

and having at the opposite side a pressure The piston I1 has a. rod 22 extending centrally from one face through the pressure chamber 23 and through a pressure head 23 closing the outer end of said chamber. A suitable packing 24 is mounted in the head 23 around ,the rod 22 to prevent leakage of fluid under pressure from the pressure .chamberZll to the atmosphere along said rod.l The outer end of the rod z2 is pivotauy connected by a pin 25 to one end of a link 28 the opposite end of which is adjustably connected by screw threads to oneend of a link 21. The opposite end of link 21 is pivotally-connected by a pin 28 t0 the gear sector II. A lock nut,29 screw-threaded on the link 21 is arranged for engagement with the end of link 28 for rigidly securing the two links in an adjusted condition,

, sector II in a counterclockwise direction, which in turn will rotate the sprocket wheels 1 and 4 and thus the maneuvering gear shaft I in a clockwise direction to provide for forward movement; ofthe craft, while movement of piston I1 from its neutral position in the opposite direcl tion or toward the left hand will cause movement of the maneuveringgear shaft I in the reverse direction to provide for astem movement of the craft.

The operation of piston I1 to move the maneuvering gear shaft I to its Idifferent positions is arranged to be effected by a diil'erential in fluid pressures provided in chambers I8 and 20 by a control valve device 32 mounted on one end of the power cylinder I 8, said control device being in turn controlled by the cooperative action of the power piston I1 and of a pilot device 33 mounted on top of the power cylinder I8, as will be later described.

'I'he control valve device 32 comprises a casing containing fluid pressure supply and release valve mechanisms 35 and 36, respectively, arranged to control, through passages I3 and 2l, the supply of v fluid under pressure to and its release from chambers I8 and 20, respectively, at opposite sides of the power piston I1.

Both ofthe valve mechanisms 35 and 36 may be of identical structure, each comprising a supply valve 31 contained in a chamber 38 which is constantly supplied with fluid at a desired reduced pressure, such as 65 pounds, from any suitable source by way of a pipe 33, a reducing valve device 40 and a, pipe 4I. Each supply valve 31 has a iluted stem 42 extending through two suitably -aligned bores provided in the casing at opposite sides of a chamber 43, and into a chamber 44.where said stem is connected by a reduced portion 45 to an axially arranged release valve 46. A plunger 41 is slidably mounted in a bore in the casing, .the chamber 44 at one side 0f the plunger constituting one end portion of this bore. Any suitable packing means (not shown) may be provided between plunger 41 and the wall of the bore to minimize leakage of fluid under pressure from chamber 44 past said plunger. The plunger 41 has a valve seat provided for engagement by the release valve 48 to close communication between chamber 44 and a passage 48 extending through the plunger and opening to a, chamber 43 at the opposite sldeof Y the plunger. The chamber 43 is in constant communication with the atmosphere.` A spring.

50 in chamber 44 acts on the plunger 41 to un seat same from the exhaust valve 46, while a spring 5I in chamber 38 acts on the supply valve 31for seating same.

The valve 31 is arranged to control ilow of i'luid under pressure from chamber 38 to chamber 43, while valve 46 ls arranged to release fluid under pressure from chamber 43 by way of thefluted stem 42 of valve 31 and thence through chamber 44 and past the valve 4B to exhaust passage 48.V

Chamber 43 in valve device 35 is connected to passage I3 leading to chamber I8 at'one side of the power piston I8, while chamber 43 in valve device 36 is connected to passage 2| leading to chamber 20 at the opposite side of power piston I1.

For controlling operation of the two valve deasaaa'rs vices 35 and 36 a lever` 52 .pivoted on a piny 53 in the casing is movable in a direction parallel to` the length of the power cylinder I6, and it will be noted that said valvel devices are located at both screws 55 and y51 are adjusted to move the plungers 41 in the respective valve devices 35 and Il downwardly into seating engagement with the release valves 46 and then a slight further adjustment of both of said screws is eiected to open thesupply valves 31 to a small degree. Fluid under pressure from the supply pipe 4.Iwill then flow past the valves 31 to passages I9 and,2l and `thence into chambers I8 and 20, respectively, at opposite sides of the power piston. l

The pressure of fluid thus obtained in chamber Il is effective past the uted stem 42 of valve 31 in chamber 44 of the valve device 35 wherein it acts on the respective plunger 41 to urge same in a directionto permit seating of the supplyvalve 31. Likewise, the pressure of fluid in chamber 20 is effective in chamber 44 of the valve device 36 wherein it acts on the respective plunger 41 to urge same in the same direction, it being noted that the fluid pressure acting on one plunger 41 opposes that on the other. When the pressure of fluid thus obtained past the supplyvvalves 31 in chambers I8 and 20 and acting on plungers 41 is `increased to a certain degree, a sufficient movement of both of said plungers will occur to permit seating of the supply valves 31 and thus prevent further flow of fluid under pressure to chambers I8 and 20.

In actual practice it has been found that a fluid same degree of pressure, said piston will be in a static condition and for instance in neutral position as shown 4in Fig. 2. These same pressures acting on the two plungers 41 also oppose and balance each other and will not therefore oppose initial movement of the lever 52 out of the neutral position shown. 1

Now let it be assumed that the lever 52 is rocked in a clockwise direction from neutral position. The operating pins 55 and 51 will move with said lever and allow the pressure of uid in chamber 44 of the valve device 36 to move the plunger q 41 thereof with the pin 51 and thus out of engagement with the respective exhaust valve 46, while in the valve device 35 the operating pin 55 will shift the plunger 41 downwardly to unseat the pressure such as fifty pounds in chambers 44 acting on the plungers 41 will create such movement or deformation of said plungers or other parts of the device asto provide for seating of the supply valves 31 if said valves are initially unseated for instance around one thousandth of an inch by adjustment of the screws 55 and 51.

It will be noted that the two plungers 41 are cpposedly connected through the adjusting screws 55 and 51 and the two arms 54 and 56, respectively, of the operating lever 52 and that such connections constitute what would commonly be considered rigid connections. The seating of the valves 31 when the plungers 41 are subjected to a certain pressure of fluid in chambers 44 is therefore considered or believed due to the elasticity of the materials in the connections between ,said

such operation is not dependent upon control springs whichhave heretofore been considered necessary, as illustrated by way of example in a `similar pneumatic control motor disclosed in my copending application No. 432,776, iiled February 28, 1942.

With the lever 52 in its neutral position shown and chambers I8 and 26 at opposite sides of the power piston I1 both chargedowith fluid at the supply valve 31. As a result of this operation fluid under pressure will be released from chamber 20 to reduce the pressureo/n one side of the power piston I1 and at the same time fluid under pressure will be supplied from the supply pipe 4I to chamber IB for increasing the pressure of fluid on the opposite side of the power piston. A differential between the fluid pressures at opposite sides of the power piston I1 will be thus created'acting in the direction of the right hand which will movesaid piston in said direction to thereby actuate the gear sector II and sprocket wheels 1 and 4 to turn the maneuvering gear shaft I in a clockwise direction.

In the operation just described it will be i noted that a minimum of effort is required to i initiate movement of the lever 52 from its neutral position due to the initial balance of fluid forces on the two plungers 41 as above mentioned, and this provides for quick response of the power piston I1 to operation of the pilot device 33 which will be later described. However after the release valve 46 in the valve device 36 is opened to reduce the pressure of iluid in the power piston chamber 20 and the supply valve 31 in the valve device 35 is opened to increase the pressure in the power piston chamber I8, the corresponding reduction in pressure on plunger 41 in the valve device 36 and increase in pressure on plunger 41 in the valve device 35 creates a force which opposes movement of the lever 52 and tends to return same to its neutral position. This is not material however since the actuating force applied to the lever by the pilot device 33, as will be later described, prevents such undesired reverse movement of thelever.

When the maneuvering gear shaft I obtainsv a desired position under the action of the power piston I1 it is necessary to stop movement of this piston andthis 'is obtained, as will be later described, by the cooperative action of said piston and the pilot device 33 to. return the lever 52 to its neutral position for again balancing the fluid pressures on opposite sides of said piston. As the lever 52 is thus returned to neutral position, the

'upward movement of the adjusting pin 55 will of for instance fifty pounds.

plunger 41 in the valve device 35 will then reduce past the respective release valve 46 until when the normal degree of fifty pounds is obtained the resiliency of the connection between The pressure in vthe power piston chamber I8 and below the the lever and s aid plunger 'will urge said plunger into seatingengagement with said release valve and thus bottle the remaining fluid in saidl chamber. At the same time that this occurs the pin 51 will actuate the valve device 36 to increase the pressure in -the power piston chamber 20 to the normal degree of for instance iifty pounds as before described, whereupon the piston I1 will be stopped, subject on opposite sidesxto fluid pressures of the same degree but less than the pressure oi the supply fluid in pipe 4I.

If the lever 52 is again rocked out of neutral position in the direction of the right hand, a differential of pressures will be again created on the power piston to move same /further toward' the right hand and such movement will cease in a position determined by when the lever 52 is rev turned to neutral position, as will be clear from the above description. It will thus be seen that the piston I1 'can be caused to turn the maneuvering gear shaft I in a clockwise direction and to stop said shaft in any position dependent lupon the return of lever 52 to its neutral position.

Only a certain diierential of fluid pressures is required on the power piston I1 to ensure operation thereof to turn the maneuvering gear shaft I, and any greater differential would result not only in waste of fluid under pressure but in an increased degree of time for balancing the opposing iiuid pressures on said piston in order to stop movement thereof in a selected position, or in other words, to prevent travel of the piston and thereby of the maneuvering gear shaft past or beyond the selected position.

This limiting of the A'differential of fluid pressures on the power piston is preferably obtained by restricting the release of fluid under pres- `sure from the one side of the power piston through the release passage 48 with respect to the rate of supply of fluid under pressure to the D- posite side. -To accomplish this the release passage 48 may be provided withA a suitable choke or restriction 68a to provide the desired reduced venting capacity and in the operation above described it will be seen that this restricted release of fluid under pressure from chamber 20 at one side of the power piston acting in conjunction with the displacement of said piston will prevent the pressure in chamber 20 becoming reduced excessively with respect to increasing pressure in chamber I 8 during movement of said piston by fluid pressure in chamber I8. The diilerential of pressures on the piston will be thus limited so that when the lever 52 is returned to neutral position, a shorter period of time, than otherwise would be necessary, will be required to increase the pressure in chamber 20 4back to the normal. degree for stopping the piston with accuracy in the desired position.

In addition to the above, the limiting of the reduction in pressure in chamber 20 also results in a corresponding limit in the reduction in ,pressure on plunger 61 of the valve device 36 and hence a like limiting of the differential of forces applied to the lever 52 by the two plungers 41, and this is desirable in that afterthe lever is out i of neutral position it minimizes the degree of force which opposes lmovement of said lever by the pilot device 33 which will be later described.

It will now be seenthat clockwisemovement of lever 52 from neutral position will cause prompt movement of the power piston toward the right hand and that this movement of said` piston will cease in a position determined by the return of lever 52 to neutral position.

If the lever 52 is moved from neutral position in a counterclockwise direction the valve device 36 will be operated to -efl'ect anfincrease in fluid pressure inchamber 20 and the valve device 35 will at the same time be operated to reduce the pressure in chamber I6 to thereby provide a differential of fluid pressures on the power pis- .ton I1 for moving same in the direction of the left hand to turn the maneuvering gear shaft I in a counterclockwise direction. Return of the lever-52 to neutral position will effect equalization oi.' the pressures on the power piston to stop same. This operation is identical in all respects to that resulting from clockwise movement oi' the lever 52 from neutral position and subsequent return to neutral position and a further description thereof is therefore not considered neces- Sary.

'I'he vpilot device 33 comprises a cylinder 66 containing a double acting piston 6I having at one side a pressure chamber 62 and at the op- -posite side a pressure chamber 63. The piston 6I lcomprises a pressure head 64, two oppositely disposed packing cups 65 mounted against opposite faces of said head and clamped thereto Iby two oppositely arranged pressure plates 66. The' pressure chamber 62 is closed by a pressure head 61 through which extends a piston `roel 66. A sui-table packing 59 is provided in the head 61 for contact with rod 68 to prevent leakage of fluid under pressure from chamber 62 along said rod tothe atmosphere. The end rod 68 in chamber 62 engages one of the pressure plates 66 and said rod is provided with a portion 66 of reduced section which extends through both of the plates 66 and the piston head 6I into pressure chamber 63. A sleeve 10 in chamber 63 is\mounted on the reduced portion 69 of the piston rod and urged against the adjacent presvsure plate 66 by a nut 1| provided on the cnd of said reduced portion for securely clamping the two packing cups 65,to the pressure head 6I.

The portion o1 chamber 63 adjacent the piston 6I is of the same diameter as chamber 62 for cooperation with said piston, 'but beyond this portion the chamber 63 is of greater diameter inA of nut 1I is also arranged to slide in lthe en\ larged portion of chamber 63 and to engage shoulder 13 provided on the end of cover 14 for limiting movement of the -Washer toward A the left hand. Interposed between and bearing against the adjacent faces of washer 11 and collar 16 outside of the sleeve 15 is a coil spring 18 arranged to oppose movement of the washer 11 in the direction of collar 16 and to also oppose movement of said collar and the sleeve 15 in the direction of said washer. Normally, that is, when |both chambers 62 and 63 are at atmospheric pressure, the spring 13 -is arranged to hold the washer 11 in contact with shoulder 1 13 and the annular collar 16 in contact with shoulder 12. Under this condition, one end of sleeve 15 is arranged to engage the adjacent face of the pilot piston 6I for thereby deiining and assaavs holding the pilot piston 8| in its neutral 4position shown in Fig. 2. v

A casing element 88 is slidably mounted in the end of sleeve opposite that' engaging piston 8|. This element has one or more slots 8| extending lengthwise thereof and the sleeve 15 is provided with a pin 82 which extends into each slot 8| for limiting movement of the element 88 outwardly of the sleeve '|5.` The outer end of the caging element 88 has an inturned spring seat 83.

A second caging element 84 is slidably mounted on sleeve 18 and freely extends through a suitable opening provided through an annular rib -85 extending inwardly from the sleeve 15. At

the end'of the caging element 84 adjacent spring seat 83l on the element 88 is an annular out- Wardly extending spring seat 85. A snap ring 81 is secured in an annular groove adjacent the opposite end of sleeve 84 and at the opposite side of rib 85 for contact with said rib.

Two coil springs 88 and 88 under a chosen degree of pressure and encircling the caging element 84 within the sleeve 15 bear at one end 'against the rib 85 on said sleeve. The opposite end of the outer spring 88 bears against the spring seat 88 provided on the caging element 88, while the opposite end of the innerl spring 88 bears against spring seat 8B provided on the caging element 84. With the piston 8| in theneutral position shown the outer spring 88 'is therefore confined under pressure between the v spring seat 83 on the caging element 88 and The end of the piston rod 58 extending beis movable to different positions indicated by legends in' Fig. l, which positions it will be noted correspond in name to the positions of the maneuvering gear shaflt I. Tworcams |82 and |83 are secured to turn with the shaft |88, the cam |82 being provided to control the operation of two directional control'or selector valve devices |84 and |85 which are operative in accordance with the direction of movement of lever |8| from its neutral position shown to selectively connect either pipe 88 or [pipe 88 to a self-lapping'valve device |88 and to open the other of said pipes to atmospl'lere,A the self-lapping valve device |88 being controlled by the cam |88.

The directional control valve devices |84 and |85 are located in the casing opposite each other and at opposite sides of the cam |82. 4Both of these devices may be of identical construction each comprising two oppositely seating poppet valves |81 and |88 contained in chambers |388 and I8. respectively. and having axially aligned nuted stems engaging each other in a chamber A spring ||2 in chamber |88 acts on the valve |81 for seating same and for at the same time unseating the valve |88. A plunger ||3 is slidably mounted in the casing and has one end en- .v gaglng cam |82 while the opposite end is disposed yond the pressure head 61 is pivotally connected by a pin 8| to a lever 82 intermediate its ends.

A rod 83 is pivotally connected at one end by a pin 84 to one end of the lever 82 while the opposite end of saidv rod is pivotally connected by a pin 85 to the end of lever 52 outside of the control valve device 32. The opposite end of lever 82 is pivotally connected by a pin 88 to one end of a link 81 the opposite end of which is pivotally connected by pin 25V to the end of the powerpiston rod 22. The link 81 provides for rocking of the lever 82 with respect to the pilot piston rod 68 and power piston rod 22, it being seen that both 'of said rods are rigidly held in parallel relation by pressure heads 61 and 23, respectively.

The pressure chamber 82 at one side of the pilot piston 8| is connected by a pipe 88 to the :manually operative selector valve device 8, while chamber 53 at the oposite side of said piston'is connected by a pipe 88 to said device.

The selector device 8 located at the operators control station, as in the pilot house of the ship and therefore remote from the pneumatic control motor I5, is provided for varying the pressure of iluid in either oi' the control pipes 88 or 88 while retaining the other of said pipes open to atmosphere, for controlling operation of motor |5 to move the maneuvering gear shaft to its dierent positions.

` 'I'he'selector valve device 8 comprises acasing in which a rockable shaft |88 is joumaled. A lever |8| is secured to shaft |88 to turn same and in chamber ||8. This plunger carries a pressure member ||4 which engages the valve |88 and a spring ||5 acting `on the pressure member for operating same .to seat said valve and unseat the valve |81 upon movement of plunger ||3 in the direction of said valves.4 With' the lever |8| and cam |82 in vtheir neutral positions shown in Fig. 1, the plunger |3 is permitted to move away from the valve |88 to provide for seating of. valve |81 and unseating of valve |88 by spring ||2. i

Initial movement of lever |8| in the' direction of the left hand imm a neutral position in which it is shown will actuate cam |82 and thereby the the lever |8| obtains the Stop position at the right hand side or its neutral position and this condition of these valves is then adapted to be maintained in all positions of said lever beyond the Stop position. When the lever |8| is rocked toward the left hand for seating the valve |88 and unseatlng the valve |81 of the valve device |84, the cam |82 provides for the valve |88 in the valve device |85 remaining open and the valve |81 remaining closed. When the lever |8|vismoved toward the Vright hand to actuate the valve device |85 the valve |88 in the valve device |84 is adapted to remain open while the valve |81is adapted to remain closed.

Chamber |88 in the valve4 device |84 :is connected by apassage ||8 to a chamber ||1 and the corresponding chamber |88 in the valve device |85 is also connected to chamber ||1 by a to the pilot device 33 while 'the corresponding ch'amber in valve device |85 is connected to the i control pipe 88 also leading to said pilot device.

|05 is open to the Iatmosphere through a passage H8.

From the above description it will be seen that upon movement of lever from its neutral position shown in the direction of the left hand the valve device |04 will connect control pipe 99 to chamber H1 while the valve device |05 will open the control pipe 98 tothe atmosphere. On the other hand if lever |0| is rocked in the direction of the right hand from neutral .position the' 10 valve device |05 will .connect the control pipe 98 vto chamber ||1 while the valve device |04 will connect the control pipe 99 to the atmosphere..

The self-lapping valve device |06 is provided for supplying iuid under pressure to chamber I I1 15 and thereby to either pipe 99 or 99 as determined by the direction of movement of the control lever |0| and the consequent operation'of the directional control valve devices |04 and |05.

The self-lapping valve device |06 comprises two 20 spaced and axially aligned ilexible diaphragms |22 and |23 which are rigidly clamped around their peripheries in the casing. Between these diaphragms is a chamber |24 whichis constantly supplied with iluid under pressure from the supply 25 stant communication through a port with 35 chamber ||1. l

A stem |3| in chamber |24 vhas one end clamped to the diaphragm |23 while .the opposite end is clamped to the diaphragm |22,` the means `clamping said stem to diaphragm |22 embodying a guide element |32 projecting through chamber |29 and slidably mounted in a bore in the lower end of a sleeve |33 which is secured in the casing in axial alignment with the two diaphragms |22 and |23 and directly below the operating shaft |00 and cam |03. v

A PODpet valve |34 is contained in a chamber |20 in the upper end of stem |3I, which chamber is constantly supplied with fluid under pressure from chamber |24 by way of passages |35 in the stem |3|. Chamber |20 also `contains a spring |36 acting on the valve |34 for urging same upwardly toward a seat provided on the adjacent end of the guide element |32.

The valve |34 has a uted stem extending through a. suitable bore in the guide element |32 into a chamber |31 provided in sleeve |33. The chamber |31 is constantly open through one or more ports |38 in sleeve |33, to the chamber ||1 which encircles said sleeve. in chamber V| 31 engages the end of the iluted stem of valve |34 and in turn has a fiuted stem |40 mounted to slide in a bore in a plunger |4 The plunger |4| is mounted to slide in sleeve |33and has suitable guide portions |42 slidably engaging the inner wall of sleeve |33. Aring shaped packing |43 disposed above the guide portions |42 is expanded into an annular groove provided in the inner wall of sleeve |33 and has sliding con- A release valvev |39 60 tact with the outer surface of plunger |4| for 70 v upper open end of sleeve |33. 'I'he bore in plunger |4| is Yopen aibove the Apacking |43 lto the atmosphere through one or more ports |44 and {,75

said bore contains a spring |46 acting on stem" |40 of the release valve |38 urging said valve in a direction out oi' said bore and thus away from its seated or closed position against the end of said plunger. V

An adjusting screw |146 is screw-threaded intb the upper end of plunger |4| and has a head |41 which engages the cam |03. A spring seat |48 is secured to the plunger |4| above the end of sleeve |46 and interposed between this seat and the casin-g is a bias spring |49 which is operative against the spring seat |48 'with a force just suilicient to urge ythe plunger |4| out of seating engagement with the release valve |38, as

shown in the drawings.

i In chamber |24 between the two flexible diaphragms I 22 and |23 is a coil control spring |54 encircling the stem |3| and having one end supported on an annular ledge |6| in the casing while the opposite end acts against the diaphragm |22 for urging same inthe direction of sleeve |33. This spring is adaptedto be fully expanded with the parts in the position shown in Fig. 1, assumed when the lever |0| is in its neutral position shown, and to oppose all movement of the ldiaphragms in a downwardly direction from this position. The two diaphragms |22 and |23 are of equal areas so that the pressure of uid in chamber |24 acting on the diaphragm |22 is opposed and balanced by said iiuid pressure acting on the diaphragm |23. Thus spring |50 provides the only force for opposing movement ofthe diaphragme in a downwardly direction.

' Operation With the lever |0| of the selector valve device in its neutral position shown, the spring |48 acting on seat |48 will urge' plunger I4| to the position shown in which said plunger is pulled 4 away from the release valve |39 due to the action of spring |45 on said valve and also to the fact that the control spring |50 is expanded toits free height thus removing the force on said valve tending to urge same in an upwardly direcy tion. Under this condition the spring |36 will hold the supply valve |34 in contact with its seat and chambers ||1 and |29 will bothlbe open to the atmosphere through ports |38. past the release valve |39 and thence through the bore in plunger |4| and parts |44.

With the selector lever |0| in its neutral position the directional control valve devices |04 and |05 will both occupy the positions shown in which 'Y i the valves |08 are unseated so that both control pipes 98 and 99 and thereby chambers 62 and 63 at opposite sides of piston 6| in the pilot device 33 will be ,open to the atmosphere.

With the opposite sides oi.' the pilot piston 4| thus subject to atmospheric pressure said piston will be held in its neutral position shown by sleeve 15 engaging one side of the piston and the washer 11 engaging nut 1|y on the end of the piston rod sleeve 'l0 under the force of spring 14 holding collar 16 on said sleeve in contact with shoulder 12 in the casing and holding the washer 11 in contact with shoulder 13 on the pressure head 14. With the pilot piston 6| in its neutral position all parts of the pneumatic control motor I5 will occupy the neutral positions shown in Fig. 2 for reasons which will be apparent from the description to follow, and accordingly, the gear sector and sprocket wheels] and 4 will occupy their neutral positions shown for corre# lpoiiilngly positioning the maneuvering gear f Start The initial movementvof lever out of neutral position actuates the cam |02 to reverse the valves of the directional control valve device |04 tothereby place the control pipe 99 in communication through passage ||6 with chamber ||1, while the directional control valve device remains in the condition shown opening the control pipe 98 to theatmosphere.

As the lever |0| is thus moved to Start position the cam |03 initially operates through 4the adjusting screw |46 to move the plunger |4| into ton rod 22 to thereby pull the operating rod 93 in the direction of the right hand. This movement `of the operating rod 93 in turn rocks the control lever 52 in the control device 32 in a corresponding or clockwise direction to thereby actuate the valve device 35 to supply fluid under pressure t0 chamber I8 and at the same time to actuate the valve device -36 to release fluid under pressure from chamber 20 for thereby establishing a difcontact with the release valve |39 and to `then move said valve along with said plunger to unseat the valve |34. The cam |03 is so designed that the supply valve |34v will thus be unseated before the lever |0| obtains the stop position.

With the'valve |34 unseated as just described fluid under pressure will flow from chamber |24 between the diaphragms past said valve to chainber |31 within sleeve |33 and then through passages |38 to chamber ||1 and from chamber |1 through passage ||6 and past valve |01 in the directional control valve device 4|||4 to pipe 99 leading to chamber 63 at one side of the pilot piston in the control motor |5. At the same time as fluid under pressure is thus supplied to chamber ||1, it also flows through port to chamber |29 at the top of diaphragm |22 and acts on said diaphragm to deect same in a downwardly direction against spring |50 thus tending to pull the guide element |32 into seating engagement with the supplyvalve |34. Such seating of valve |34 may be provided for by the time the pressure of fluid in chamber |29 and thus in the control pipe S9 is built` up to a chosen degree such as seventyfive pounds, or if desired, the cam |03 may beso designed as to maintain valve |34 open with the lever |0| in Start position so that fluid at the relatively high pressure, of for instance one-hundred pounds, supplied by the reducing valve device |25 may be obtained in the control pipe 99.

Fluid at this high pressure obtained in pipe 99 flows to chamber 63 at the left hand side of the pilot piston 6| and acts thereon to move said piston to an extreme right hand position defined by contact between the washer 11 and the left hand end of sleeve 15. As the piston 6| thus moves it will be seen that the initial portion of its movement `is opposed only by the spring 18 following which the washer 11 will engage the adjacent end of caging element 80 and then move same relative to the sleeve 15 so that continued movement of the piston will be opposed by both springs 18 and 89. After a certain degree of this continued movement the washer 18 will engage the end of the caging element 84,so that further movement of the piston toits extreme right hand position will then be opposed by all of the springs 18,` 89

nd 88; A a The power piston I1 has a greater resistance to movement than lever 52 and the valve mechanisms 35 or 36 in the control device 32, as a result of which movement of the pilot piston 6| in the direction of the right -handwill rock the lever 92 about its fulcrum connection with the power pis.

ferential of fluid pressures' on the power piston |1 for moving same in the direction of the right hand to operate the gear sector and sprocket wheels 1 and 4to turn the maneuvering gear shaft in a clockwise direction and thus in the direction of the arrow indicated by the legend Ahead which corresponds to the direction of movement;

of the lever I0 As the power piston I1 is end of the equalizing lever 92, and after the pilot piston 6| obtains its extreme right hand position above described, said lever is rocked by the power piston I1 in a counterclockwise direction about its fulcrum connection with the pilot piston rod 68 and thus actuates the rod 93 to turn the lever 52 in a counterclockwise direction back toward its neutral position which will be obtained when the power piston obtains a position in which the maneuvering gear shaft is in Start position. When the lever 52 is returned to its neutral position as just mentioned, the valve devices 35 and 36 are conditioned as above described toV equalize the fluid pressures on the opposite sides of the power piston |1 due to which movement of said piston will stop in a position determined by the position of the pilotpiston and hence in accordance with the selected position of the selector lever-lOl.

When the pilot piston 6| is moved its full stroke 'as just described the corresponding movement of the power piston |1 will operate the gear sector and therebythe sprocket wheel 1 and connected sprocket wheel 4 to turn the maneuvering gear shaft to its Start position in which the engine will be started or placed in motion in a direction for propelling the craft forwardly.

It will now be seen that movement of the operating lever 0| in the direction indicated by the legend Ahead" in Fig. 1 and to the position indicated by the legend Start at the left hand side vering control shaft in the direction indicated by the legend fAhead and to the position indicated by the legend Start, the direction of movement of and the position obtained fior the maneuvering shaft therefore corresponding to the direction of movement and position of the operating lever |0| of the selector device |08.

After the engine has been put in motion for causing forward movement of the craft, the lever |0| will be returned from the Start position to the adjacent position indicated by the legend Full or to any other desired speed position intermediate said Full and the next adjacent position indicated by the legend Slow. As the lever |0| is thus moved from Start position in a clockwise direction, the cam |03 permits spring |49 acting on the plunger |48 to move said plunger upwardly and away from the exhaust valve |39, said valve being held against l moved in the direction y, of the right hand it carries with it the lower der pressure will be released from the pilot piston chamber 63 through pipe 99 and the directional control valve vdevice |04 to chamber ||1 and thence past the release valve |38 to the at,-

pressure in the pilot piston chamber 63 in a po-` sition of said plunger determined by the position of cam |03 and oi lever |0I. Ii' the lever |0| is merely moved to the Full position the exhaust valve |39 will become seated whenthe pressure acting on the pilot piston 63 and thereby in chamber |29 on diaphragm |22 becomes reduced to a certain pressure, such as'for instance iiftytwo pounds. If, however, the lever is moved to the "Slow position the spring |49 acting on the plunger |4| will be permitted 'to raise said plunger to a position where the pressure acting on the pilot piston 63 and in chamber |29 above the diaphragm4 |22 will become reduced to a pressure such as seventeen pounds. Intermediate positions of the plunger |4| obtained in different positions of lever |0| between the "Full" and lSlow" positions will provide for seating o! the exhaust valve |39 when the pressure lin chamber |29 above the diaphragm and'thus in chamber 63 at one side of the pilot piston becomes reduced to corresponding intermediate pressures, between the fifty-two and seventeen that with the lever |0| in the Full" speed position at the left hand side ot its neutral position the washer 11 will be just in engagement with spring seat 86 on the caging element I4, but the lo* spring 89 acting on said seat will be ineil'ective on the pilot piston 6|, while when the lever |0| is in the Slow position the washer 11 will be justin contact with spring seat 83 on the caging element 80 and lthe spring 88 will be ineffective on said piston. For all intermediate positions of lever |0I the washer 11 will assume a position opposed and determined by both springs 18 and 88, but unopposed by spring 88 acting on the caging element 84.

Let it be assumed that lever |0| has been returned from Start" position to Full" position as a result of which the pilot piston 6|v will be moved by springs 18 and 88 to a position in which the washer 11 is just in contact with spring seat 86 on the caging element 84 with the lock washer 81 in contact with rib 85 of the sleeve 1.6. This movement of the pilot piston 8| acts to turn the lever 82 in acounter-clockwisel direction about pounds pressures obtained in the Full "and l of springs-18,` 88 and 89 on the washer 11 overbalances the pressure ofuid on the pilot piston 6| and pulls said piston in the direction of the left hand until at the time the pressure of such fluid becomes reduced to the` high limit of tlftytwo pounds above mentioned, the snapv ring 81 on the caging element 84 will have contacted the rib 85 of sleeve 15 and thus removed the force of spring 89 from the washer 11. If the pressure of fluid in chamber 83 at one side of the pilot piston is further reduced said piston will be moved under the action of springs 88 and 18 until at the time such pressure is reduced to the seventeen pounds above mentioned, the pressure of spring 88 willA have been removed from washer 11 due to the caging element 80 engaging pins 82 in sleeve 15.

As above *mentioned the springs 88 and 89 are assembled in the pilot device under a certain degree of precompression, such as for instance of a degree equivalent to vepounds iluid pressure on the pilot piston 6|. The seventeen and fifty-two pounds pressures supplied by the selector device in the Slow and Full" positions is approximately two and one-half pounds less than required to move the pilot piston 6| against the springs 88 and 89respectively, and therefore substantially midway between the pressure required to move said piston into contact with the cages 80 and 84 and to then move said cages. A variation from the seventeen and fifty-two pounds either above or below these values of for instance two pounds will therefore have no effect the fulcrum connection with the power piston rod 22 to cause a corresponding rocking movement of the control lever 62 of the control device Y 32 for thereby actuating the valve'device 38 to supply fluid under pressure to chamber I8 at the lei't hand face of the power piston l1 and for at the same time effecting 'operation of the valve device 35 to lrelease uid under pressure from chamber 20 at the opposite side-ot the power piston. A dierential of fluid pressures will thereby` be created on the power piston to movev the washer 11, movement o! the power piston I1 to turn lever 52 back to its neutral position for equalizing the fluid pressures on the power piston so asto stop said piston in a position corresponding to the position of the pilot piston 6| and th Full position of lever |0|.

As the power piston |1 is thus moved from its extreme right hand position toward the left hand it operates the gear sector to turn the sprocket wheels 1 and 4 and thereby the maneuvering gear shaft from its Start position in a counterclockwise direction and this movement will cease when said shaft obtains its Full" position since opposing iluid pressures on the power piston l1 will be equalized at this time.

Now let it 'be assumed that the lever |0| -is returned from "FulP position to Slow position to thereby reduce the pressure of fluid in chamber 63 at the left hand face of the pilot piston 6| to the low degree oi seventeen pounds above mentioned. The force of springs 18 and 88 on washer 11 in the pilot device will then move the piston 6| further toward the left hand toa position in which the caging element 80 just comes into contact with the pins 82 in which position it will stop as required by the position oi' lever |0l. This movement of the pilot piston 8| will again operate the lever 92 and thereby the control device 32 to again Vsupply iiuid under preson the opposite face for causing movement of the piston further in the direction of the left hand and this movement will continue until the control lever 52 is again returned to neutral position for equalizing the fluid pressures on the power piston, which will occur in a, position of said piston corresponding to the position in which the pilot piston 6| was stopped.` 'I'his further movement of the power piston |1 toward the left hand will effect a corresponding operation of the gear sector and sprocket wheels 1 and 4 to turn the maneuvering gearA shai't to its Slow position in which it will be stopped due to the power piston I1 being stopped and it should be noted that this position corresponds to that called for by the position of lever lill.

It will be readily seen that if the control lever lill is moved to any position intermediate Full and Slow the proportional pressure provided in chamber' 63 on the pilot piston 6| will provide a corresponding positioning of said piston against the combined opposing forces of springs 'I8 and 86, and that the valve device i2 and power piston l1 will respond to adjust the maneuvering gear shaft l to a corresponding position between Full and "Slow" positions. Thus by operation of lever ll in the zone between Full and Slow positions to vary the pressure of fluid in chamber 53 on the pilot piston 6| between limits such as the Vnifty-two and seventeen pounds above mentioned, the pilot piston 8| will be positioned to provide for corresponding positioning of the power piston i1 and of the maneuvering gear shaft l to vary the speed or power output of the engine being controlled,

If now the operator desires to stop the engine, he moves the lever to the position indicated by the legend Stop" and the cam |03 Iis so designed that in this position a further reduction in fluid pressure, to a chosen low degree such as ten pounds,`will be effected in pipe 99 and pilot piston chamber 63 by operation of the self-lapping control valve device |06', as a result of which the spring 18, now alone effective on washer 11, will move said washer to a position intermediate the spring seat 83 on theycaging element 80 and the shoulder 13 to therebycorrespondingly position the pilot piston 6I foril'ectlng operation of the power piston I1 in the same manner as above described to actuate the gear sector and sprocket wheels 1 and 4 to return the maneuvering gear shaft I to its "Stop" position for stopping the respective engine. This position is not critical like the Slow and Full positions above described'so that positive position'dening means is not required for same.

After the engine is stopped the lever |0| may be returned to its neutral `position in which the self-lapping valve device |06 opens chamber ||1 to the atmosphere and the cam |02 provides for operation of the directional control` device |04 to open pipe 99 and pilot piston chamber 63 to atmosphere. The opposite faces of the pilot piston 6| will then both be subject to atmospheric pressure so that the pressure of spring 18 on the Washer 11 will move same into contact with shoulder 13 on the cover 14 and thereby return the pilot piston 8| to its neutral position. This movement of the pilot piston 6| will operate the lever 92 and thereby the control valve device 32 in the same manner as before described to cause movement of the power piston |1 back to its neutral position for effecting operation of the gear sector |I and thereby the sprocket wheels 1 and 4 to return the maneuvering gear shaft I to its neutral position.

If the operator now desires to move the craft in an astern directionI he rocks the lever |0| from the neutral position shown in a clockwise direction, as indicated by the arrow bearing the legend "Astern," to the Start position at the right hand side of the selector device 6. This operation of lever |0| actuates the selector valve device |05 to connect the control pipe 9 8 to chamber I|1 and also operates the self-lapping valve device |06 inthe same manner as vbefore described for supplying fluid under pressure to the pipe 98 and thence to chamber 62 at the right hand side of the pilot piston 6|. At this time chamber 63 at the left hand side of the pilot piston is open to the atmosphere by way of pipe 99 and the selector valve device it.

'I'he pressure of fluid thus supplied to chamber 62 at the right hand side of the pilot piston moves said piston in the direction of the left hand'to a position in which the left hand end of sleeve 15 engages the washer 11, the spring 18 opposing such movement throughout the full stroke of the piston 6l and the springs 86 and 89 becoming successively eiective to oppose such movement upon engagement of spring seat 83 on the caging element with the washer 'l1 and subsequent engagement of spring seat 86 on the caging element 8d with said Washer.

'Ihis movement of the pilot piston operates the lever 02 and thereby the control device 32 to supply fluid under pressure tochamber 20 and to release fluid under pressure from chamber i8 at opposite sides of the power piston l1 for thereby moving said piston to its extreme left hand position in which fluid pressures in said chambers will be again equalized by operation of the control valve device 32, this operation of lthe control device 3'2 and power piston l1 being substantially like that before described, as will be seen. This movement of the power piston l1 in turn operates the gear sector. and sprocket wheels 1 and 4 to turn the maneuvering gear shaft I in a clockwise direction from its Neutral position t0 the position indicated by the legend "Start at the left hand side of the vertical center line of gear 4. The engine will therefore be started in the direction to cause astern movement of the craft.

After the engine is thus put in motion, the lever |0| is returned to either Full or Slow position, or to an intermediate' position at the right hand side of said lever for thereby reducing the pressure of iluid acting on the right hand side of the pilot piston 6|, as a result of which said piston will be moved toward the right to a position depending upon the reduced pressure of iiuid in chamber 62. For instance if the lever is in Full" position the pilot piston will assume a position where the snap ring 81 in the caging element 84 will be in contact with rib 85 in sleeve 15 while spring seat 86 at the opposite end of said caging element will be just in contact with washer 11. If the lever is moved to the "Slow" position, the piston 6I will assume a position in which the caging element 80 will be in contact with pins 62 in the sleeve 15 and also in conta'ct with the washer 11. For all intermediate positions of lever |0| the caging element 80 will be `disengaged from the pins 82 butin contact with the washer 18. ".lhus .the position of the pilot' piston 6|, for all positions of the lever |0| between Full and Slow' positions at the right hand side of the neutral position, is determined by the combined action of springs 88 and 18' and speed; l

the opposing pressure 'of uid supplied by the selector valve device 6, the same as above described for movement of the craft forwardly.

It will be seen that when the lever is moved in the direction of the left hand to cause movement of the craft .Ahead the sleeve in the pilot device remains stationary and the washer 11 moves with `the pilot piston 6|, while upon movement of the lever |0| in the direction of the right hand for causing Astern movement of the craft the washer 11 remains stationary while the sleeve 15 is moved with the piston 6|. In both cases however the spring 18 opposes all movement of the pilot piston from neutral position while the springs 88 and 89 are successively rendered effective vupon an increase in pressure on the pilot pistonor ineffective upon a reduction in pressure on-the pilot piston, in the same order and to accomplish lthe same results for both directions of movement of lever I0| and thereby ofthe pilot piston 6|.

` When the pilotpiston 6| moves from its neutral position toward the left hand to a position corresponding to the position of the control lever IUI at the right hand side of its neutral position -between Slow and "Full positions, the lever 92 and control valve device 32 will be operated to cause a corresponding positioning of the power piston VI1 and thereby of the -gear sector II, sprocket wheels 1 and 4 and maneuvering gear shaft I, in the same manner as before described as will be readily seen,

If during Astern movement of the craft the 1 operator desires to stop the engine, he moves the lever ||l| to the Stop position at the right hand side of the Aneutral position to thereby reduce the pressure in the control pipe 98 for positioning the pilot piston 6| to cause a corresponding positioning' of power piston I1 and thereby of the operator may then move the lever back to its neutral position for completely releasing fluid under pressure from the pipe 98 by way of the selector valve device ||J5 and thereby from chamber 62 at the right hand face of the pilot piston 6|. The pilot piston 6| will then be returned to its neutral position by spring 18 following which the power piston |1 will be operated to its neutral position for returning the maneuvering gear shaft I to its "Neutral position.

If the craft is being propelled in a forwardly direction and the operator desires to reverse the direction of movement, he may do so by moving the lever |0| from Whatever position it may oceupy at the left hand side of neutral position tov tion and the operator desires to reverse the direction of movement, he will merely move lever |0| from the position it may occupy at the right side of its neutral position to the Start position at the vopposite side of the neutral position and then back into a selected position in the zone between Full and "Slow" positions following which the control motor I5 will operate to correspondingly position the maneuvering gear shaft I in a manner which will be evident from the above description.

In order that the pilot of the craft may be aware of the integrity or proper operation of the control system I associate with the control valve device 32 two switches |51 and |58, one located at one side of the llever 52 for operation thereby upon movement in one direction and the other located at the opposite side of the lever for operation by the lever upon movement inthe opposite direction. Each of these switches, may be of identical structure comprising, diagrammatically, a contact Aelement |66 arrangedto be operated by lever 52 upon movement out ofjits neutral posi- -tion to electrically connecttwo xed' contacts |6| and |62. A spring |63 acting oneach of the contact elements |66 is provided for actuating the element out of bridging relation with the conresponse to movement of the lever |0| out of its neutral position will cause operation of the buzzer |66 to indicate t0 the pilot that the pilot device 33 and control'device 32 associated therewith are operating as intended. When the power piston |1 then moves to the position determined by the position of the pilot piston 6| and the lever 52 is returned to neutral position, the circuit to the buzzer |66 will be opened and said. buzzer will stop sounding to indicate to the pilot that the power piston I1 has operated as intended and therefore the maneuvering gear shaft l has been moved to the desiredposition. It will be seen that if the apparatus operates as intended in rel sponse to movement of the control lever |0| in either direction, the buzzer |66 will be caused to operate and then stop operating. In case the buzzer 66 fails to operate at alll the pilot's attention will be directed to the fact that the pilot device 3,3 or control device 32 is not operating as required or that some other part of the system is out of order, such for example as the circuit to the buzzer or possibly failure of the fluid pressure supply to the selector device 6 or to pipe 98 -or 99, whereupon suitable measures may be ing control shaft to its Start position at the left hand side of the vertical center-line of said shaft occurs, the operator may move the lever |0I, back to Full, Slow or any desired intermediate speed position at the right hand side of the neutral position 'for causing movement of the craft in an astern direction at a desired rate of `In case the craft is moving in an astern direcpromptly taken to correct the fault. Further, if the buzzer 66 starts operating in response to operation of the control device 32, but ceases to stop the operator is made aware of the fact that some part of the system beyond the control device 32 is not operating as intended, as for instance failure of the power pistony I1 to move.

In addition to the above I provide a pneumatically controlled switch device |61 controlled by the reduced pressure of fluid in pipe 4| tocause operation of the buzzer |66 in case the pressure in the said pipe becomes reduced to a degree below'a chosen value.`

This'device'comprises a piston |66 having at one side a chamberA |69 in constant communication through pipe with pipe 4| whereby the piston |68 is constantly subject on one face to the pressure of iluid supplied by the reducing valve device 4|!` to pipe 4|. 'I'he opposite side Vof piston |68 is subject to the pressure of a spring I1 I, which is of such value as to provide for movement of the piston |66 to the position shown if the pressure in pipe 4| is above a chosen sate degree; but to move piston |88 in the direction of chamber |68 in case the pressure in pipe 4I is at a lower degree.

The piston |68 is connected by a stem |12 to a movable switch contact |13 which is arranged to electrically connect two fixed contacts |14 and |15 upon movement of the piston |68 to its lower position and to open the circuit between such con tacts when mits upper position shown. The contact |15 is connected to the battery |64 while the contact |14 is connected to wire |65 leading to the buzzer |66. By this arrangement. the contact |13 will be held out of engagement with contacts |14 and |15 whenever the pressure of iiuid supplied by the reducing valve device 40 to pipe 4| is at or above a safe degree, but in case this pressure becomes reduced to below the safe degree, movement of the piston |68 to its lower position will move contact |13 into engagement with the contacts |14 and |16 for connecting the battery |64 to the buzzer |68 to cause operation of said buzzer and thereby call the pilots attention 3 to the low pressure condition in the system. A

cutout switch |16 is provided in wire |65 to render the buzzer |66 inoperative when the system is void of fluid under pressure.

Summary i pilots selector device to cause positioning of said -member in accordance with a chosen operation of the selector device. I associate with the power means a plurality oi' springs arranged to become successively ellective or to be rendered succespositions, said piston means having positions corresponding to the positions of said device, a plurality of precompressed springs one arranged to oppose all movement of said means by pressure of fluid and another arranged to become effective on said piston means to also oppose pressure of fluid thereon in a position of said piston means corresponding to a chosen position of said device, and means for varying the pressure of fluid on said piston means and having a position for providing fluid on said piston means at a pressure for creating in the said position of said piston means a force exceeding that oi' the said one spring but less than the combined forces of said one spring and of the other spring.

2. Power means for selectively effecting movement of a device'to a plurality of different positions including a neutral position comprising a casing double acting piston means in said casing for actuating said device and having positions corresponding to the positions of said device and being movable to the different positions at one side of neutral positions by fluid under pressure sively ineffective to provide for accurate posi- `means which controls the member being operated may with accuracy move said member to the se Vlected position. In order to insure that the operator will be always aware of the operative con dition of the system and thus minimize the possibility of failure of the system in use, I provide means for indicating whether or not the pressure of fluid in the system is adequate and f"or also indicating whether the mechanism operates as intended in response to a selected operation of the operator.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. Power means for selectively moving a device to any one of a plurality of different positions comprising in combination, a casing, piston means in said casing movable by fluid under' pressure to effect movement of said device to its different acting one one side tol eifect movement of said device to the corresponding positions and being operable by fluid under pressure acting on the opposite side to effect movement of said device to the corresponding position at the opposite side 4 of its neutral position, a spring acting on said piston means opposing all movement thereof by iluid pressure and operative with opposite: sides of said piston means subject to the same pressures to move said piston means to its neutral position to correspondingly position said device, and another spring arranged to become eiective in a certain one of the positions of the said piston means at both sides of its neutral position to also oppose movement of said piston means, the said other spring being precompress'ed and therefore operative to require a certain increase in pressure on said piston means to overcome same and a like reduction in pressure on said piston means to render same ineffective for thereby defining said one position of said piston means to correspondingly position said device.

3. Power means for selectively controlling the positioning of a device movable to a plurality of different positions including a neutral position comprising a casing, double acting piston means in said casing having positions corresponding to those of said device and being movable to said positions by fluid pressure acting either on one side or the opposite to effect movement of said device to its corresponding positions, a spring opposing all movement of said piston means in either direction and operable with opposite sides of said piston means subject to atmospheric pressure to move said piston means to its neutral position to correspondingly position said device, and another spring .pre-compressed and arranged to become effective in a certain position of said piston means at both sides of neutral position to oppose further movement of said piston means from neutral position, said other spring upon becoming eiective requiring a certain increase in pressure on said piston means to continue movement thereof,

'and requiring after movement of said piston means ceases under the action of both said springs, a corresponding reduction in pressure on said piston means to render same movable by the first named spring for thereby rendering the second named spring effective to deiine said certain position of said piston means at either side of its neutral position, and a manual control means selectively operable to vary the pressure of iluid on either side of said piston means while opening the opposite side of said piston means to atmosphere, said manual control means having positions corresponding to the positions of said device and being operable in each position to provide Huid to act on said piston means ata pressure forl moving same to a corresponding position and operable in the position corresponding to said certain position of said piston means to provide uid .under pressure adequate to render said pre-compressed spring effective to oppose further movement of said piston means but inadequate to effect such. further movement.

4. `A control device comprising in combination a casing, piston means in said casing movable in one direction upon supply of fluid under pressure to one side and in the oppositeV direction upon supply of fluid under pressure to the opposite side, a pre-compressed spring in said casing interposed between said piston means and casing for opposing movement of said piston means in either direction from aneutral position by uid under Vmovement, thereof in the opposite direction and the one or other member not movable with said piston being supported by said casing against movement, a pre-compressed spring interposed between said two members for opposing movement of said piston in either one direction or in the opposite direction, a caging element associated with pressure, andone or more other pre-compressed springs in said casing cooperative with the first named spring in certain positions of said piston means at both sides of said neutral position to deiine said certain positions.

5. A control device comprising in combination a casing, a double acting piston in said casing having a neutral position and arranged to be moved one of said members and having telescopic movement therewith, a. second pre-compressed spring interposed between said caging element and the last named member urging said caging element out of telescopic relation with said last named member, means for limiting movement of sa=d caging elementout of telescopic relation with said last named member to provide for engagement be-- tween the other member and said caging element after a certain movement of said piston means in either direction from neutral position to render the second named springr effective to oppose further movement of said piston means in either direction from neutral position.

ROY R. STEVENS. 

